If you haven't heard of it before, Earth Hour is a yearly event held the last Saturday of March, from 8:30 to 9:30 PM local time, and is celebrated by turning off the lights for an hour. Being only an hour, it isn't meant to have a great impact on electricity being used, but more to spur conversations with friends and… »3/26/11 12:00pm 3/26/11 12:00pm